Isolated Oral Histoplasmosis Masquerading as Acute Necrotizing Gingivitis

Histoplasmosis is a dimorphic fungal infection caused by Histoplasma capsulatum, commonly found in soil enriched with bird or bat droppings. While pulmonary involvement is typical, oral manifestations occur in 30%–50% of disseminated cases [1]. These lesions are usually seen in immunocompromised hosts. Primary oral histoplasmosis in an immunocompetent individual, that too solely in the form of desquamative necrotising gingivitis, is distinctly rare. A 52-year-old man, a chronic smoker for 30 years, presented with painful gingivitis and nonhealing ulcers of the palate and buccal mucosa that had progressively worsened over 8 months. The illness began with ulceration of the right upper gingiva, which gradually spread to involve both arches. A dentist attributed the condition to poor oral hygiene. However, despite several courses of antibiotics, his symptoms persisted. Three months later, he consulted a dermatology clinic, where a clinical diagnosis of desquamative gingivitis secondary to pemphigus vulgaris was made, and systemic corticosteroids were initiated. One month later, he presented to our dermatology outpatient department with worsening disease—multiple painful, foul-smelling ulcers on the hard palate, soft palate, and buccal mucosa. He denied any history of fever, weight loss, gastrointestinal, or respiratory complaints. Intraoral examination revealed poor oral hygiene with multiple carious teeth and severe desquamative gingivitis affecting both arches. Numerous irregular ulcers with erythematous indurated margins and hypertrophic granulation tissue at the base were present over the gingiva, buccal mucosa, and palate (Figure 1a,b). Bleeding occurred on probing. Mild cervical lymphadenopathy was present, but systemic examination was unremarkable. Hemogram, renal and liver function tests were normal, and viral serologies for human immunodeficiency virus, hepatitis B virus, and hepatitis C virus were negative. Given the poor response to prior therapy, differentials considered included necrotising ulcerative gingivitis secondary to pemphigus vulgaris/vegetans, squamous cell carcinoma, granulomatosis with polyangiitis, oral tuberculosis, oral lesions of Crohn's disease, necrotizing sialometaplasia, and deep fungal infections. Tzanck smear was noncontributory. Biopsy revealed hyperplastic squamous epithelium with dense lymphoplasmacytic infiltrate and numerous intracellular organisms consistent with Histoplasma (periodic acid–Schiff positive) (Figure 2a,b). Direct immunofluorescence for immunoglobulin (Ig) G, Ig A, IgM, and complement C3 was negative. Magnetic resonance imaging of the face showed an ill-defined infiltrating heterogeneously enhancing lesion in the gingivo-buccal region with focal maxillary bone erosion and extension toward the maxillary sinus (Figure 2c,d). Computed tomography of the thorax revealed only smoking-related changes. A diagnosis of primary oral histoplasmosis was made. The patient was started on itraconazole 200 mg twice daily, leading to near-complete healing within 4 weeks (Figure 1c,d). Histoplasmosis manifests as acute pulmonary, chronic pulmonary, or disseminated forms. Oral lesions are usually part of disseminated disease but may mimic more common causes of desquamative gingivitis, such as pemphigus vulgaris, cicatricial pemphigoid, oral lichen planus, or gingival squamous cell carcinoma [2]. Classically, oral histoplasmosis appears as painful ulcerated papules and plaques arranged linearly along the buccal mucosa. In their review of 21 cases, Kamboj et al. [3] noted that virtually all patients had ulcerative lesions, most often involving the tongue, buccal mucosa, and palate. On an extensive literature review, we were able to find only a single case report of necrotizing ulcerative gingivitis as the sole presentation of oral histoplasmosis [4]. Khetarpal et al. [4] reported a case masquerading as acute necrotizing ulcerative gingivitis, but with cutaneous involvement—a feature absent in our patient. To the best of our knowledge, this is the first documented case of isolated oral histoplasmosis presenting as desquamative necrotising gingivitis with maxillary bone erosion in an immunocompetent host. This expands the known spectrum of oral histoplasmosis and highlights the diagnostic challenge it poses when it closely mimics more common inflammatory and autoimmune gingival disorders. Histopathology remains the diagnostic cornerstone, with periodic acid–Schiff or Gomori methenamine silver aiding identification of yeast forms. In our patient, biopsy confirmed the presence of Histoplasma organisms. Management depends on severity and host status. Amphotericin B is reserved for severe or disseminated cases, while itraconazole is preferred for localized disease [5]. The patient received itraconazole for a total duration of 6 months. Therapy was discontinued at that point as complete clinical resolution had been achieved by the third month of therapy, and in the subsequent 3 months of follow-up, no evidence of persistent or recurrent disease was noted. We have not used artificial intelligence. We have referred to the publisher's policy of use of AI as depicted in information for authors and assume full responsibility for the content of our manuscript, even those parts produced by an AI tool, and are thus liable for any breach of publication ethics. The authors have nothing to report. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.